/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.google.android.exoplayer2.ext.ffmpeg;

import static com.google.android.exoplayer2.audio.AudioSink.SINK_FORMAT_SUPPORTED_DIRECTLY;
import static com.google.android.exoplayer2.audio.AudioSink.SINK_FORMAT_SUPPORTED_WITH_TRANSCODING;
import static com.google.android.exoplayer2.audio.AudioSink.SINK_FORMAT_UNSUPPORTED;

import android.os.Handler;

import androidx.annotation.Nullable;

import com.google.android.exoplayer2.C;
import com.google.android.exoplayer2.Format;
import com.google.android.exoplayer2.audio.AudioProcessor;
import com.google.android.exoplayer2.audio.AudioRendererEventListener;
import com.google.android.exoplayer2.audio.AudioSink;
import com.google.android.exoplayer2.audio.AudioSink.SinkFormatSupport;
import com.google.android.exoplayer2.audio.DecoderAudioRenderer;
import com.google.android.exoplayer2.audio.DefaultAudioSink;
import com.google.android.exoplayer2.decoder.CryptoConfig;
import com.google.android.exoplayer2.util.Assertions;
import com.google.android.exoplayer2.util.MimeTypes;
import com.google.android.exoplayer2.util.TraceUtil;
import com.google.android.exoplayer2.util.Util;

/**
 * Decodes and renders audio using FFmpeg.
 */
public final class FfmpegAudioRenderer extends DecoderAudioRenderer<FfmpegAudioDecoder> {

    private static final String TAG = "FfmpegAudioRenderer";

    /**
     * The number of input and output buffers.
     */
    private static final int NUM_BUFFERS = 16;
    /**
     * The default input buffer size.
     */
    private static final int DEFAULT_INPUT_BUFFER_SIZE = 960 * 6;

    public FfmpegAudioRenderer() {
        this(/* eventHandler= */ null, /* eventListener= */ null);
    }

    /**
     * Creates a new instance.
     *
     * @param eventHandler    A handler to use when delivering events to {@code eventListener}. May be
     *                        null if delivery of events is not required.
     * @param eventListener   A listener of events. May be null if delivery of events is not required.
     * @param audioProcessors Optional {@link AudioProcessor}s that will process audio before output.
     */
    public FfmpegAudioRenderer(
            @Nullable Handler eventHandler,
            @Nullable AudioRendererEventListener eventListener,
            AudioProcessor... audioProcessors) {
        this(
                eventHandler,
                eventListener,
                new DefaultAudioSink.Builder().setAudioProcessors(audioProcessors).build());
    }

    /**
     * Creates a new instance.
     *
     * @param eventHandler  A handler to use when delivering events to {@code eventListener}. May be
     *                      null if delivery of events is not required.
     * @param eventListener A listener of events. May be null if delivery of events is not required.
     * @param audioSink     The sink to which audio will be output.
     */
    public FfmpegAudioRenderer(
            @Nullable Handler eventHandler,
            @Nullable AudioRendererEventListener eventListener,
            AudioSink audioSink) {
        super(eventHandler, eventListener, audioSink);
    }

    @Override
    public String getName() {
        return TAG;
    }

    @Override
    protected @C.FormatSupport int supportsFormatInternal(Format format) {
        String mimeType = Assertions.checkNotNull(format.sampleMimeType);
        if (!FfmpegLibrary.isAvailable() || !MimeTypes.isAudio(mimeType)) {
            return C.FORMAT_UNSUPPORTED_TYPE;
        } else if (!FfmpegLibrary.supportsFormat(mimeType)
                || (!sinkSupportsFormat(format, C.ENCODING_PCM_16BIT)
                && !sinkSupportsFormat(format, C.ENCODING_PCM_FLOAT))) {
            return C.FORMAT_UNSUPPORTED_SUBTYPE;
        } else if (format.cryptoType != C.CRYPTO_TYPE_NONE) {
            return C.FORMAT_UNSUPPORTED_DRM;
        } else {
            return C.FORMAT_HANDLED;
        }
    }

    @Override
    public @AdaptiveSupport int supportsMixedMimeTypeAdaptation() {
        return ADAPTIVE_NOT_SEAMLESS;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected FfmpegAudioDecoder createDecoder(Format format, @Nullable CryptoConfig cryptoConfig)
            throws FfmpegDecoderException {
        TraceUtil.beginSection("createFfmpegAudioDecoder");
        int initialInputBufferSize =
                format.maxInputSize != Format.NO_VALUE ? format.maxInputSize : DEFAULT_INPUT_BUFFER_SIZE;
        FfmpegAudioDecoder decoder =
                new FfmpegAudioDecoder(
                        format, NUM_BUFFERS, NUM_BUFFERS, initialInputBufferSize, shouldOutputFloat(format));
        TraceUtil.endSection();
        return decoder;
    }

    /**
     * {@inheritDoc}
     */
    @Override
    protected Format getOutputFormat(FfmpegAudioDecoder decoder) {
        Assertions.checkNotNull(decoder);
        return new Format.Builder()
                .setSampleMimeType(MimeTypes.AUDIO_RAW)
                .setChannelCount(decoder.getChannelCount())
                .setSampleRate(decoder.getSampleRate())
                .setPcmEncoding(decoder.getEncoding())
                .build();
    }

    /**
     * Returns whether the renderer's {@link AudioSink} supports the PCM format that will be output
     * from the decoder for the given input format and requested output encoding.
     */
    private boolean sinkSupportsFormat(Format inputFormat, @C.PcmEncoding int pcmEncoding) {
        return sinkSupportsFormat(
                Util.getPcmFormat(pcmEncoding, inputFormat.channelCount, inputFormat.sampleRate));
    }

    private boolean shouldOutputFloat(Format inputFormat) {
        if (!sinkSupportsFormat(inputFormat, C.ENCODING_PCM_16BIT)) {
            // We have no choice because the sink doesn't support 16-bit integer PCM.
            return true;
        }

        @SinkFormatSupport
        int formatSupport =
                getSinkFormatSupport(
                        Util.getPcmFormat(
                                C.ENCODING_PCM_FLOAT, inputFormat.channelCount, inputFormat.sampleRate));
        switch (formatSupport) {
            case SINK_FORMAT_SUPPORTED_DIRECTLY:
                // AC-3 is always 16-bit, so there's no point using floating point. Assume that it's worth
                // using for all other formats.
                return !MimeTypes.AUDIO_AC3.equals(inputFormat.sampleMimeType);
            case SINK_FORMAT_UNSUPPORTED:
            case SINK_FORMAT_SUPPORTED_WITH_TRANSCODING:
            default:
                // Always prefer 16-bit PCM if the sink does not provide direct support for floating point.
                return false;
        }
    }

}